The handset will cost €69 (around $90), which includes a pre-pay balance of €30 for prepaid customers plus a 4GB microSD card. The carrier is also offering an option of zero interest financing for post-paid customers. IHS Screen Digest analyst Ian Fogg described the pricing as “very compelling, commenting on the launch via Twitter: “Featurephones are dead, finally… Now there’s no price reason not to own a smartphone.”

Telefonica said it also plans to offer the handset in additional markets ” in the coming weeks” — name-checking Colombia and Venezuela. When it announced support for Firefox OS back in February it said its first Firefox-powered phones would be sold in Latin America and Spain. In the event, Spain gets first dibs. Also today, Telefonica confirmed the ZTE Open will be the first of “a number of Firefox OS devices” it will launch this year — “across a range of different price points”. Which suggests it’s also hoping to challenge Android’s expansive mid-tier, although this first handset sits firmly in the low end segment.

Commenting on the launch in a statement, Luis Miguel Gilpérez, CEO of Telefónica España, said: “We believe that smartphones need to be more open and that the web is the platform for making this possible. Consumers should not be locked to any one system but have the choice to consume the content they want and the flexibility to be able to take it with them when they change devices. This first open web device marks a significant milestone in making this possible. This is just the beginning as we plan to bring a wide range of Firefox OS devices to our customers.”

This is not the only diversification effort Telefonica has made in the smartphone space in recent times. Just last week it announced a joint marketing effort with Microsoft to push the Windows Phone 8 platform in a bid to dilute the power of Android and iOS. Firefox OS can be seen as another branch of the same strategy, as carriers seek ways to erode the dominance Google especially has established in smartphones. Figures out today from Kantar peg Android’s smartphone share in five European markets at 70%, for instance.

Too much power concentrated in the hands of a single company weakens the position of carriers — giving them an incentive to push alternatives. Unlike Android, Firefox OS’s openness offers them a vehicle for adding and promoting their own services without having to put more power in the hands of Google.

Specs wise, the ZTE Open is a low end affair, with a 3.5-inch, HVGA TFT touchscreen display, 256MB of RAM and 512MB of ROM combined with a 3.2MP camera. Location-based services are provided by Nokia’s HERE maps. Firefox OS can run HTML 5 apps — with optimized versions of Facebook and Twitter available, along with the likes of Pulse, Airbnb and Soundcloud to name a few. Additional local apps can be sourced via the Firefox Marketplace.

The ZTE Open is not the first phone running Firefox OS to go on sale. Spanish developer phone startup, Geeksphone, put out two developer handsets running the OS back in April, selling out of its stock within hours. But this is the first commercial device launch of a device running the Firefox OS.

Mozilla said Deutsche Telekom is also preparing to launch a Firefox OS devices, in the first wave of launches along with Telefonica. The other handset touted to be landing in this launch phase is the Alcatel One Touch Fire. The OS currently has more than 20 hardware and operator backers globally. Mozilla added that carrier Telenor will launch their first Firefox OS phones in Central and Eastern Europe this year.